U2 frontman Bono and guitarist The Edge insist the formula for the band's success is simple - all four members have an enormous ego.The Irish rockers have been together for 31 years without splitting up to pursue solo projects. And The Edge has shed light on the reason for their apparent loyalty - each member thinks U2 is his band. He says, "(Drummer) Larry (Mullen, Jr.) started the band, so Larry reckons it's his band. But (bassist) Adam (Clayton) was the first manager so he sees it as his band. It goes without saying that Bono sees it as his band. The actual truth is, and I'm far too modest to say this, but it's my band." Bono adds the group's joint enthusiasm for perfection rules out any discrepancy over who takes credit for their success. He says, "The thing about four egos, which I guess you must have if you want to be in a band, is that in this case the band's ego is bigger than that of the individual members. "We share the songwriting, it's sort of a hippy communal idea and has been since we were 17 or 18, so people don't seem to care who's idea that was or who wrote that song, as long as it's the best idea."